Cromones

The drugs cromolyn sodium (Intal) and nedocromil sodium (Tilade) are commonly grouped together as chromones (also called cromoglycates). The best known specific action of chromones is their ability to block or attenuate the effects of immunologic and non-immunologic stimuli in both asthmatics and normal individuals. For example, they have potent effects in preventing both early and late asthmatic responses to inhaled allergens such as pollen, and they reduce airway reactivity resulting from exposure to a range of inhaled irritants such as sulfur dioxide and cold air.

Their precise mechanism of action is not known. The current hypotheses proposed to explain the mechanism of drug action and effect include:

1. The drug enhances phosphorylation of a cell membrane protein that is responsible for the termination of mediator release from mast cells (stabilization of the mast cell membrane).

2. Chromones suppress firing of sensory C-fiber nerve endings.

3. Cromones have variable inhibitory actions on other inflammatory cells that may participate in allergic inflammation including macrophages and eosinophils.

4. Chromones inhibit the synthesis of IgE antibody by B-lymphocytes.

Cromones are widely used in pediatrics, but have suffered from limited efficacy in adult populations. These agents are extremely safe, and side effects are extremely rare. The two chromones are available for inhalation by either metered dose inhaler or nebulizer solution. Both require QID dosing.

Category: Pharmacology Notes